Texas law breaks up controlled substances into "penalty groups," and it looks like your co-worker has been charged with possession of something that may fall in either penalty group 1 or penalty group 2.
The full list of the controlled substances assigned to each penalty group is in the Texas Health and Safety Code, which is available online and linked below. Unfortunately, it makes for pretty dry reading; you might need to brush up on your chemistry to make sense of it.
PG stands for Penalty Grade - which is another way of saying how dangerous the drug is and what could be the possible sentencing range if convicted. I believe the charge is saying either PG 1 or 2 but that would be an incorrect manner in which to indict because the defendant is entitled to know what he is being charged with having committed.